Peripheral Vascular Stent Insertion

Various peripheral arterial occlusive lesions have traditionally been managed with surgical therapy. However, endoluminal intervention with catheter-based techniques has become quite common and, in many cases, is now the treatment of choice. Several interventional products are available for the endovascular specialist, but balloons and stents make up the core of these technologies.

Placement of a metal stent across a stenotic or occluded blood vessel is intended to maintain the patency of the vessel and reestablish flow through it by providing internal structural support. This article discusses the indications, contraindications, anesthesia, necessary equipment, positioning, techniques, and potential complications of endovascular stent placement in peripheral vessels.

The indications for peripheral vascular stent placement in a patient with known peripheral arterial disease (PAD) are the same as those for open intervention.

Indications for vascular stents in the lower extremities are as follows:

• Severe, debilitating claudication
• Lifestyle-limiting claudication refractory to lifestyle modification and exercise regimen
• Ischemia with rest pain
• Ischemic nonhealing lower-extremity ulcers

Indications for vascular stents in the upper extremities are as follows:

• Severe arm claudication with subclavian stenosis
• Syncope or dizziness with arm use ( subclavian steal syndrome) with evidence of subclavian stenosis and retrograde vertebral flow
• Ischemic ulcers of the hand

Indications for vascular stents in the visceral arteries are as follows:

• Difficult-to-control hypertension on three or more medications with or without elevated creatinine levels; greater than 60% renal artery stenosis
• Mesenteric ischemia (postprandial abdominal pain, weight loss, “food fear”) and more than 70% stenosis in the celiac or superior mesenteric artery

Indications for vascular stents in the carotid arteries are as follows:

• Most carotid stent procedures are being performed as part of clinical trials
• Stent therapy for carotid stenosis is reserved for patients at high operative risk (eg, intervention for restenosis following previous surgical repair, prior radiation to the neck, high lesions that are difficult to access surgically, or contralateral carotid occlusion)

Selective stent placement (exclusive of carotid intervention) is indicated as a secondary intervention following balloon angioplasty when the result is residual stenosis greater than 30% or a flow-limiting dissection.

Primary stent placement is generally indicated as initial intervention for iliac, renal, subclavian, and carotid stenosis.

The Trans-Atlantic Inter-Society Consensus II (TASC II) ^[1] established recommended guidelines for treatment of peripheral vascular disease on the basis of lesion characteristics. An update published in 2015 expanded the TASC classification to include arteries below the knee. ^[2]

The TASC classification for aortoiliac lesions is as follows:

• TASC A - Unilateral or bilateral stenosis of the common iliac artery (CIA); unilateral or bilateral single short (≤ 3 cm) stenosis of the external iliac artery (EIA)
• TASC B - Short (≤ 3 cm) stenosis of the infrarenal aorta; unilateral CIA occlusion; single or multiple stenosis totaling 3-10 cm involving the EIA but not the common femoral artery (CFA); unilateral EIA occlusion not involving the origins of the internal iliac artery (IIA) or CFA
• TASC C - Bilateral CIA occlusions; bilateral EIA stenosis 3-10 cm long not extending into the CFA; unilateral EIA stenosis extending into the CFA; unilateral EIA occlusion involving the origins of the IIA or CFA; heavily calcified EIA occlusion with or without involvement of the orogins of the CFA or IIA
• TASC D - Infrarenal aortoiliac occlusion; diffuse disease involving the aorta and both iliac arteries; diffuse multiple stenosis involving the unilateral CIA, EIA, and CFA; unilateral occlusion of both CIA and EIA; bilateral EIA occlusions; iliac stenosis in patients with an abdominal aortic aneurysm (AAA) requiring treatment that is not amenable to endograft placement

The TASC classification for femoropopliteal lesions is as follows:

• TASC A - Single stenosis ≤ 10 cm long; single occlusion ≤ 5 cm long
• TASC B - Multiple stenoses or occlusions, each ≤ 5 cm; single stenosis or occlusion ≤ 15 cm not involving the infrageniculate popliteal artery; heavily calcified occlusion ≤ 5 cm long; single popliteal stenosis
• TASC C - Multiple stenoses or occlusions totaling >15 cm with or without heavy calcification; recurrent stenosis or occlusions after failure of treatment
• TASC D - Chronic total occlusions of the CFA or the superficial femoral artery (SFA) >20 cm, involving the popliteal artery; chronic total occlusion of the popliteal artery and proximal trifurcation vessels

The TASC classification for infrapopliteal lesions (with the anterior tibial artery as the selected example) is as follows:

• TASC A - Single focal stenosis ≤ 5 cm long in the target tibial artery with occlusion or stenosis of similar or worse severity in the other tibial arteries
• TASC B - Multiple stenoses, each ≤ 5 cm long or total length ≤ 10 cm, or a single occlusion ≤ 3 cm long in the target tibial artery with occlusion or stenosis of similar or worse severity in the other tibial arteries
• TASC C - Multiple stenoses in the target tibial artery and/or a single occlusion with total lesion length >10 cm with occlusion or stenosis of similar or worse severity in the other tibial arteries
• TASC D - Multiple occlusions involving the target tibial artery with a total lesion length >10 cm or dense lesion calcification or nonvisualization of collaterals; the other tibial arteries are occluded or have dense lesion calcification

Preferred treatment is as follows:

• TASC A lesions - Endovascular therapy is the treatment of choice
• TASC B lesions - Endovascular therapy is the preferred treatment, but this depends on patient comorbidities, fully informed patient preference, and the operator’s long-term success rate
• TASC C lesions - Surgery is the preferred treatment for good-risk patients, but this depends on patient comorbidities, fully informed patient preference, and the operator’s long-term success rate
• TASC D lesions - Surgery is the treatment of choice

There has been an increase in the adoption of an endovascular-first approach for even complex (TASC C/D) lesions. However, more and better-quality data comparing open with endovascular therapy are needed, particularly with regard to meaningful outcomes (eg, limb viability, wound healing, quality of life, and survival) besides anatomic patency. ^[2]  The STELLA SUPERA (STEnting Long de L'Artère fémorale superficielle par le stent métallique Supera) trial has provided information on 24-month outcomes, though the need for randomized clinical trials remains. ^[3]  

No absolute contraindications for using stents in the peripheral vessels exist. Recommendations against the use of stents for peripheral intervention are outlined in the general guidelines for high-category TASC lesions listed above (see Indications).

Other limiting factors may relate more to those that would be considered in any angiographic procedure, such as renal insufficiency, which may limit the ability to use iodinated contrast for the procedure, or pregnancy, which would contraindicate the use of radiation.

It generally is not recommended to place stents across areas of extreme flexion or compression points that could lead to stent crushing and fracture—for instance, across the inguinal ligament (CFA) or across the knee flexion point in the popliteal artery (which is actually proximal to the knee joint itself). Again, most limitations are based on guidelines only and must be assessed on a case-to-case basis.

Self-expanding stents are preferred for long lesions, tortuous vessels, or areas where concern for external forces or compression exists. Such stents are more flexible, more trackable, and available in much longer lengths (currently in the range of 2-17 cm for a single stent); these are ideal for femoral-popliteal lesions.

Balloon-expandable stents are recommended for ostial lesions, calcified lesions, and short-segment lesions because they can be deployed precisely and exert a stronger radial force; these are ideal for treatment of renal, mesenteric, iliac, and subclavian lesions.

If stent insertion is considered a likely possibility, a minimum sheath diameter of 6 French should be considered.

In the treatment of contralateral femoral-popliteal lesions, a long sheath extending to the contralateral CFA gives a more stable position through which to work. A meta-analysis by Antoniou et al demonstrated that drug-eluting stents yielded better short-term results than bare-metal stents, with increased patency and freedom from target lesion revascularization (TLR); the influence on end points such as limb salvage remains unknown. ^[4]

In treating subclavian, mesenteric, and renal lesions, a guide catheter is useful to help track a balloon-expandable stent to the desired vessel; this requires a larger-diameter sheath to accommodate the guide catheter of the required diameter.

Treatment of aortic lesions can be done with Palmaz stents (large-diameter balloon-expandable stents that must be manually mounted onto a large balloon) ^[5] ; alternatively, one can consider covered stent grafts such as those used for aortic aneurysmal disease.

Venous stenting has also shown benefit in certain cases ^[6] ; this is mostly seen in iliac vein stenosis (eg, May-Thurner syndrome) and can be performed with larger-diameter Wallstents with much more significant oversizing (≥25%) because veins have much higher capacitance.

Decision-making should always take into consideration the possibility that an endovascular intervention might limit future surgical options. For example, placement of a stent in the CFA or the below-the-knee popliteal artery could limit the option of a bypass in the future and thus should probably be avoided. ^[7]

A retrospective analysis by Haine et al compared interwoven nitinol stents (INS) with drug-eluting stents (DES) in patients with femoropopliteal lesions. ^[8] The primary endpoint was time to clinically driven TLR (CD-TLR) within 12 months. Secondary endpoints were time to death, amputation and composite of death, amputation and CD-TLR. At 12 months, the cumulative incidence of CD-TLR did not differ in the two groups. One stent was not determined to be pteferable to the other, even for calcified or popliteal artery lesions.

A retrospective cohort analysis by Phair et al evaluated paclitaxel drug-eluting stent implantation (DES) and angioplasty with drug (paclitaxel)-coated balloons (DCB) in the treatment of 97 patients with long-segment (>100 mm) femoropopliteal disease (Rutherford III-VI). ^[9]  After the initial procedure, patients were followed for target lesion restenosis (>50% reduction in lumen diameter on duplex ultrasonography). Cumulative primary patency was 87% at at 6 months and 71% at 12 months. The corresponding figures for DES were 88% and 80%, respectively, and those for DCB were 81% and 49%.

In the STELLA SUPERA trial, a prospective two-center single-arm study (N = 48; 49 lesions) aimed at assessing the clinical safety and efficiency of the Supera stent in the treatment of long femoropopliteal (TASC C/D) lesions in patients with symptomatic PAD at 24 months, Nasr et al found the device to be safe and effective. ^[3]  At 12 and 24 months, the primary sustained clinical improvement rate was 87.2% at 12 months and 79.7% at 24 months. At 24 months, the primary patency rate was 77.9%, and the rate of freedom from TLR was 86.9%.